Transformer circuit for balancing current flow through parallel semiconductors



3 Sheets-Sheet l Xn PRIOR ART SATOSHI SHIMADA .ZZZZVEHZ'UZT' 6a fos/n'Shim ddd TRANSFORMER CIRCUIT FOR BALANCING CURRENT FLOW THROUGH PARALLELSEMICONDUCTORS Now-17, 1964 Filed Aug. 24, 1960 PRIOR ART R l l l X:

I E T -z I I 2 Nov. 17, 1964 SATOSHI SHIMADA 3,157,817

TRANSFORMER CIRCUIT FOR BALANCING CURRENT FLOW THROUGH PARALLELSEMICONDUCTORS Filed Aug. 24. 1960 3 Sheets-Sheet 2 fiyanfar" Safes/71'Sh/mada Nov. 17, 1964 SATOSHI SHIMADA TRANSFORMER CIRCUIT FOR BALANCINGCURRENT Filed Aug. 24. 1960 7 :1 5 PRIOR ART D FLOW THROUGH PARALLELSEMICONDUCTORS 3 Sheets-Sheet 5 Safes/w S/u'mada United States PatentTRANSFORMER CIRCUIT FOR BALANCING CUR- RENT FLOW THROUGH PARALLELSEMICON- DUCTORS Satoshi Shimada, Tokyo, Japan, assignor to SonyCorporation, Tokyo, Japan, a corporation of Japan Filed Aug. 24, 1960,Ser. No. 51,576 Claims priority, application Japan Aug. 24, 1959 3Claims. (Cl. 315-27) This invention relates to a semiconductor parallelconnection system and more particularly to a transistor parallelamplifier or diode parallel connection.

One object of this invention is to provide a transistor parallelamplifier which is adapted for an audio amplifier or deflection outputamplifier in a television receiving apparatus.

Another object of this invention is to provide a transistor parallelamplifier, in which unbalanced amplification due to the difference ofthe characteristics of respective transistors connected in parallel iscompensated to obtain stable parallel amplifying operation.

A still further object of this invention is to provide a diode parallelconnection which is operated under stable and balanced condition.

Another object of this invention is to provide a combined connectionsystem of a parallel transistor amplifier and a parallel diode device,which is adapted for a defiection output circuit in a televisionreceiving apparatus.

Further objects, features and advantages of this invention will be moreapparent from the description taken in connection with the accompanyingdrawing in which,

FIG. 1 is a connection diagram of one example of transistor parallelamplifiers heretofore known.

FIG. 2 is a connection diagram of another example of conventionaltransistor parallel amplifiers.

FIG. 3 is a schematic diagram of the device according to this invention.

FIG. 4 is a connection diagram of a transistor parallel amplifier, byway of example, according to this invention.

FIG. 5 is a connection diagram of another transistor parallel amplifieraccording to this invention.

FIG. 6 is a connection diagram of a further example of transistorparallel amplifiers according to this invention.

FIG. 7 is a connection diagram of a still further example of transistorparallel amplifiers according to this invention in which threetransistors are connected in parallel.

FIG. 8 is a connection diagram of a transistor parallel amplifieraccording to this invention in which four transistors are connected inparallel.

FIG. 9 is a connection diagram of one example of diode parallelconnections heretofore known.

FIG. 10 is a connection diagram of a diode parallel connection device,by way of example, according to this invention.

FIG. 11 is a connection diagram of another diode parallel connectiondevice according to this invention.

FIG. 12 is a connection diagram of a further example of diode parallelconnection systems according to this invention, and

FIG. 13 is a connection diagram of a diode parallel connection systemaccording to this invention, applied to a horizontal deflection outputamplifier in a television receiving apparatus.

Before entering into the description of this invention, I will explainsome of the transistor parallel amplifiers heretofore known, referringto FIGS. 1 and 2. In order 3,157,817. Patented Nov. 17, 1964 to amplifyan electric power by an amplifier, which has transistors connected inparallel, it has been usual to use such an amplifier as shown in FIG. 1,in which input terminals or bases of a plurality of transistors X X Xare connected in parallel to an input signal source e; the output sidesor the collectors are connected in parallel to a load L and the emittersthereof are also connected in parallel and earthed. 1 is adirect-current source and 2 represents a bias source for the bases ofthe transistors.

In such a parallel amplifier as shown in FIG. 1, substantially the sameamplifying output cannot be obtained from individual transistors owingto the characteristic differences of transistors, especially adifierence of input resistance, the current amplifying factors on and,8. Accordingly one of the transistors is so overloaded that temperaturerise occurs in its operation, by which the transistor becomes moreunbalanced. Thus a conventional parallel amplifier has the disadvantagethat a stable amplifying operation can not be expected.

In order to avoid this defect due to the aforesaid unbalance, resistorsR R R in the amplifier have been connected respectively to emitters ofthe transistors X X X and earthed as shown in FIG. 2. In such aconnection, however, it is only for controlling a current which flowsthrough the unbalanced transistor, and the power loss, owing to theresistor insertion, is inevitable. Consequently such a parallelamplifier has not yet been sufiicient.

The above mentioned defects can be recognized in a diode parallelconnection system. In order to let the current flow through each diodeby connecting a plurality of diodes in parallel to each other, it hasbeen usual in a conventional device that resistors R R R arerespectively connected in series to the diodes D D D as shown in FIG. 9,and that these series circuits are arranged in parallel relationship andthus the unbalance of the corresponding current of the diodes due to thedifierence of internal resistances of the respective diodes is adjustedby the resistor connected to each diode. It is inconvenient, however, toinsert the resistors in series to the diodes because high power lossoccurs due to the resistors.

Considering the above fact, this invention is intended to eliminate theabove mentioned defects. Now I will explain the principle of thisinvention referring to FIG. 3 in which S and S represent respectivelysemiconductors for example such as transistors. The input electrodes mand m are connected in parallel to an input signal source e, and theoutput electrodes in and n are also connected in parallel with eachother and to one terminal of the load L through electric source 1. Theother output electrodes 0 and 0 are connected to the other terminal ofthe load L through electromagnetic coupling means T which is representedas a transformer in this example. Namely the electrodes 0 and 0 arerespectively connected to both ends of the transformer T, theintermediate point P of which is connected to one terminal of the load Las shown in the drawing.

In the above connection, 1 and I designate respectively output currentspassing respectively through the semiconductors S and S E and Erepresent respectively the voltage across the electrodes 0 and n and Oand n due to the currents I and I Assuming that P, and P representrespectively the power dissipation in operation of the semiconductors Sand S and assuming (P max. and (P max., the maximum allowable powerdissipa tion of the same, then the following formulae can be generallyobtained:

In accordance with this invention the turn ratio of the parts t and t ofthe transformer T is so selected as to establish the following formula:

(P max. P

(P max.=(P max.

the intermediate point P may be selected as the neutral point of thetransformer T. In the parallel connection system using diodes, sameprinciple of this invention will be understood even if the inputelectrodes m and m and the relative connection thereof will be dispensedwith.

Now, the parallel connection system using transistors will be explainedas follows; in this case, bases and collectors of a plurality oftransistors are respectively connected in parallel, and emitters arealso connected in parallel through electromagnetic coupling elements,whereby a conductive change of an unbalanced transistor will control theother transistors through the electromagnetic coupling element to obtaina balanced parallel amplifying effect among them.

In case of using two transistors X and X as shown in FIG. 4, the basesand collectors thereof are respectively connected in parallel; forinstance, input signal source a is connected commonly to the bases and aload L is inserted commonly to the collectors of the transistors.Emitters of the two transistors are respectively connected to theopposite ends of an electromagnetic coupling element or transformer coilT and the substantial neutral point P of the coil is earthed.

According to the above mentioned connection, signals from the signalsource e are respectively amplified in parallel at the transistors X andX and parallel amplified outputs are supplied to the load L. In thiscase, if characteristics of the two transistors X and X are equal, therespective emitter currents are equal and accordingly voltages of thesame potential will be delivered to the emitters.

If, however, one of the two transistors, X for example, becomesunbalanced with respect to the other transistor X due to a change of 13,and amplified current of the transistor X is increased, with the resultthat the emitter current will be also increased.

In this case the potential of one end of a coil part t between theneutral point P and the emitter of the transistor X varies more in thenegative direction so that the potential of the emitter goes to morenegative direction from its previous potential. At the same time thevoltage change occurred in the coil part 1 causes an induction change ofthe potential in the other coil part 1 between the neutral point P andthe emitter of the transistor X whereby electric potential with respectto the emitter of the transistor X is changed to the positive directionquite reversely to the above mentioned.

Thus, by the parallel amplifier according to this invention, theincrease of an output current of the transistor X which enters in anunbalanced condition is compensated, and the output current of thetransistor X is increased, whereby the two transistors are maintainedetfectively in a balanced condition.

The above description has been mainly made in connection with thetransistors X and X having substantially equal maximum power dissipation(P max. and (P max. respectively, but if (P max. and (P max. areunequal, the turn ratio of the parts t and t may be so selected that itis inversely proportional to that of (P max. and (P max., whereby thedesired balanced and stable parallel connection amplifier is obtained.

An amplifier shown in FIG. 5 is constructed as an emitter follower typein which a load L is connected to a neutral point P of a transformer Tand one end of which is earthed. The corresponding parts of this type ofthe amplifier to those of the amplifier shown in FIG. 4 are indicatedwith the same reference numerals as in FIG. 4. The transistors performthe same parallel amplifying operation with a balanced relationship asthe former embodiment shown in FIG. 4.

FIG. 6 shows another amplifier constructed as a base earthed parallelamplifier, in which the neutral point P of the transformer T connectedto an emitter is connected to an input signal source 2. In such a case,the amplifier is so operated that unbalance of either one of thetransistors to the other may be detected by the transformer T and thatthe two transistors may get in a balanced condition to each other.

It will be noted in this example that the output current is passingthrough source l-bias source Z-signal source etransformer T-emitters andcollectors of the transistors X and X load L-source 1.

I have explained parallel amplifiers using two transistors, but FIG. 7shows a further embodiment in which three transistors are connected inparallel and a transformer T is inserted between the neutral point P ofa transformer T which is arranged between emitters of the abovementioned transistors X and X and the emitter of a transistor X In thisamplifier, the transistors X X and X are respectively in a balancedcondition to one another; that is, a divided point P of the ratio of 2:1is earthed.

The operation of this amplifier is the same as previously described andaccordingly a further explanation will be omitted for the sake ofsimplicity.

FIG. 8 shows an amplifier having four transistors and the connectionthereof will be easily understood from the drawing. Moreover, it will beapparent that a parallel amplifier with a desired number of transistorscan be so constructed as to operate in the same manner as hereinbeforedescribed. Transistors of both P-N-P type and N-P-N type can be used inthis invention.

It is apparent, of course, that this invention can be adapted for aparallel amplifier of an emitter earthed type, of a base earthed typeand of a collector earthed one.

I have explained mainly transistor parallel connection amplifiers, butthe principle of this invention can also be applied to diode parallelconnection systems.

Now, such a diode parallel connection device according to this inventionwill be explained as follows:

In FIG. 10, respective negative electrodes, for instance, of the twodiodes D and D are connected in parallel to a terminal a; the positiveelectrodes, on the other hand, are respectively connected to both endsof an electromagnetic coupling element, namely a transformer T; theneutral point P is connected to a terminal b so that the two diodes areconnected in parallel.

If a proper voltage is impressed across the terminals a and b in theabove connection, a current I +I flows in the direction shown by thearrow A through the diodes D and D At this time if the internalresistances of the two diodes are equal to each other, the current offlows through the diodes respectively.

If, however, the internal resistance of one of the two diodes, D forinstance, is small or reduced, the two diodes are in such an unbalancedcondition that the current more than will flow through the diode DAccordingly, the electric potential of one end of the coil part betweenthe neutral point P and the diode D varies more in the negativedirection and the electric potential of the positive electrode of thediode D goes to the more negative direction from the previous potential.At the same time, the voltage change occurred in the coil part t isinduced to a coil part 1 whereby the positive electrode potential of thediode D is turned to the positive direction quite reversely to theabove-mentioned. Thus the current passing through the diode D iscontrolled to be decreased and the current passing through the diode Dis increased, whereby the two diodes are maintained efiectively in abalanced condition to each other.

FIG. 11 shows an example in which the electromagnetic coupling element Tis arranged on the negative electrode side of the diodes D and Dsimilarly to the above description and the operation thereof is the sameas that mentioned above.

FIG. 12 shows another example in which three diodes D D and D are used.The same electromagnetic coupling element T as that aforesaid isarranged between the neutral point P of the coil inserted between diodesD and D and the diode D and a divided point P of the ratio 2:1 at whichthe diodes D D and D are respectively in the balanced condition isconnected to the terminal a. Since the operation of this embodiment isthe same as the previously described, a further detailed explanationwill be omitted.

It will be also noted in the diode parallel connection system that abalanced and stable operation will be expected, even in the case ofusing diodes having different maximum allowable power dissipations witheach other, by only selecting the turn ratio of the parts t and tcorresponding to the characteristics of the diodes, in the same manneras described in the parallel connection system using transistors.

Referring to FIG. 13, I will continue the explanation of this inventionfor the case in which the device of this invention is applied to ahorizontal deflection output circuit in a television receivingapparatus. 11 is a horizontal deflection signal input transformer, 12 isa transistor amplifier, 13 is a diode parallel connection deviceaccording to this invention and 15 is a horizontal deflecting coil whichis a load. The transistor amplifier 12 is constructed as a parallelamplifier, in which bases of the respective transistors X and X areconnected in parallel to each other and connected to the inputtransformer. The collectors of the transistors are also connected inparallel and further connected to the load L, to which a diode parallelconnection device according to this invention is connected in thereverse direction. Between the emitters of the transistor is inserted anelectromagnetic coupling element T; which is the same as that in theaforementioned example of FIG. 4 and the neutral point P thereof beingearthed. This transistor parallel amplifier is also constructed in thesame manner as previously mentioned in which the unbalance between thetransistors can be decreased.

The operation of this example will be easily understood from thedescription hereinbefore made referring to FIG. 4.

According to the above-mentioned connection, the diodes D and D willeffect as a damper to the horizontal deflecting coil 15, namely, the twodiodes will become conductive with the balanced relationship and effectaccurate damper action.

The diodes D and D actuating as dampers may be respectively connected inthe reverse direction with respect to the transistors X and X across theemitters and collectors thereof in the circuit shown in FIG. 4.

Although I have hereinbefore explained some examples in which two orthree diodes are used, it will be easily understood that the sameoperation and effect as those previously mentioned can be obtained bythe connection system in which any desired number of diodes are used inparallel.

It will be understood that many modifications and variations may beeflected without departing from the scope of the novel conceptions ofthis invention.

What is claimed is:

1. In a semiconductor parallel connection system,

a pair of transistors each having first, second and third electrodes,

first, second and third circuit points,

means connecting both of said first electrodes to said first circuitpoint,

transformer means including two inductively coupled windings connectedbetween said second electrodes and said second circuit point,

means connecting both of said third electrodes to said third circuitpoint,

a deflection coil,

a supply voltage source,

means including said deflection coil and said supply voltage sourceconnected in series between said first and second circuit points,

and means for applying a horizontal deflection signal between said thirdcircuit point and one of the other circuit points to control currentflow between said first and second electrodes and thereby controlcurrent flow through said deflection coil.

2. In a semiconductor parallel connection system,

a pair of transistors each having first, second and third electrodes,

first, second and third circuit points,

means connecting both of said first electrodes to said first circuitpoint,

transformer means including two inductively coupled windings connectedbetween said second electrodes and said second circuit point,

means connecting both of said third electrodes to said third circuitpoint,

a deflection coil,

a supply voltage source,

means including said deflection coil and said supply voltage sourceconnected in series between said first and second circuit points,

means for applying a horizontal deflection signal between said thirdcircuit point and one of the other circuit points to control currentflow between said first and second electrodes and thereby controlcurrent flow through said deflection coil,

a pair of semiconductor diodes having first and second electrodes,second transformer means including two inductively coupled windingsconnected between said first electrodes of said diode and said secondcircuit point,

and means connecting said second electrodes of said diodes to said firstcircuit point.

3. In a television deflection coil system,

first and second circuit points,

deflection coil means and a supply voltage source connected in seriesbetween said first and second circuit points,

a pair of diodes each having first and second terminals,

a pair of transistors each having base, collector and emitterelectrodes,

means for applying a horizontal deflection signal between said baseelectrodes of both of said transistors and said first circuit point,

first means connecting said first terminals of said diodes and saidemitter electrodes of said transistors to said first circuit point,

and second means connecting said second terminals of said diodes andsaid collector electrodes of both of said transistors to said secondcircuit point,

one of said first and second means including transformer means havingfirst winding means in circuit with one of said transistors and one 7 8of said diodes and second winding means in ReferencesCited in the fileof this patent of said transistors and the P said first and secondwinding means being 2,005,875 SflYerman t- June 1935 connected inopposed relation to increase 5 2,666,819 K Q 1954 the current throughone of said diodes and 2,921,231 Prelslg 1960 one of said transistors inresponse to in- 2,926,267 Radchfie eta-1 Feb-23,1950 creased currentthrough the other of said 2,941,154 Rogers J1me 1960 diodes and theother of said transistors.

1. IN A SEMICONDUCTOR PARALLEL CONNECTION SYSTEM, A PAIR OF TRANSISTORSEACH HAVING FIRST, SECOND AND THIRD ELECTRODES, FIRST, SECOND AND THIRDCURCUIT POINTS, MEANS CONNECTING BOTH OF SAID FIRST ELECTRODES TO SAIDFIRST CIRCUIT POINT, TRANSFORMER MEANS INCLUDING TWO INDUCTIVELY COUPLEDWINDINGS CONNECTED BETWEEN SAID SECOND ELECTRODES AND SAID SECONDCIRCUIT POINT, MEANS CONNECTING BOTH OF SAID THIRD ELECTRODES TO SAIDTHIRD CIRCUIT POINT, A DEFLECTION COIL, A SUPPLY VOLTAGE SOURCE, MEANSINCLUDING SAID DEFLECTION COIL AND SAID SUPPLY VOLTAGE SOURCE CONNECTEDIN SERIES BETWEEN SAID FIRST AND SECOND CIRCUIT POINTS, AND MEANS FORAPPLYING A HORIZONTAL DEFLECTION SIGNAL BETWEEN SAID THIRD CIRCUIT POINTAND ONE OF THE OTHER CIRCUIT POINTS TO CONTROL CURRENT FLOW BETWEEN SAIDFIRST AND SECOND ELECTRODES AND THEREBY CONTROL CURRENT FLOW THROUGHSAID DEFLECTION COIL.